Customer Retention
 

Calculating Retention Equity with RFM Analysis

Computation of retention equity using an RFM model follows these eight steps:

Step 1:
Identify a cohort of customers to be analyzed. Generally, all customers in the cohort should have been acquired within the same time period.
  Step 2: Create the "cells" for the RFM analysis.
  Step 3:

Create an RFM matrix for the customer cohort.

  Step 4: Set the number of purchase events for which the analysis will be conducted (e.g., four future purchases).
  Step 5: Generate all of the nodes of the decision tree. (The base of every branch is a node; that is, every point of choice between alternatives is a node.)
  Step 6: For every node and terminal state, compute the probability that the customer will reach it. (A terminal state marks the end of a complete purchase path.)
  Step 7: Compute the profitability of a customer at each terminal state.
  Step 8: Compute the expected retention equity per customer by multiplying the probability that a customer will reach a given terminal state times the payout once the customer has reached it.
The example of Firm C will illustrate these steps.
Step 1:
Identify a cohort of customers to be analyzed. Generally, all customers in the cohort should have been acquired within the same time period. Firm C selected as its cohort 1,000 customers acquired in 1995.
Step 2: Create the cells for RFM analysis. The cells must be mutually exclusive, meaning that a customer has a clear path to follow. In this case, the cells were based only on recency and frequency, as shown in Table Retention-8. With each first purchase, a path began with the customer entering the one-time, 0-6 months cell. From there, the customer became either a two-time buyer with 0-6 months recency or a one-time buyer with 7-12 months recency.

Adding a monetary value component to the framework would have increased the complexity of the analysis. For example, if the firm had decided to add cells based on purchase amount (e.g., purchases worth $0 to $100 versus those worth more than $100), the number of cells in Table Retention-8 would have doubled. It is important to note that, depending on how firms define monetary value in the RFM structure, a customer could increase the frequency of purchases but still remain at the same level of monetary value. For example, a customer could spend $25 on the first purchase and $25 on the next purchase. Using the monetary value breakdown noted above, this customer would have a frequency of 2 but still remain in the monetary value classification of $0-$100. Firms typically measure monetary value over a specified time horizon. For example, the monetary value variable might be defined as the total monetary value of the customer's last year of purchases.
Step 3: Create an RFM matrix for the customer cohort. The specific probabilities for this example appear in Table Retention-8. The probabilities represent the likelihood that a customer will be in that cell at any given time.
Step 4: Set the number of purchase events for which the analysis will be conducted. Here, for simplicity's sake, the analysis covers only two years. If this were a real-world analysis, a computer program would run the computations for projections of five to ten years.
Step 5: Generate all of the nodes of the decision tree. There are 16 nodes in this example's decision tree, as shown in Table Retention-9.
Step 6: For every node and terminal state, compute the probability that the customer will reach it.

The probability that a customer will reach a particular node, described as "current state" in Table Retention-9, equals the probability that the customer reached the prior node times the probability of the buying decision made by the customer at that prior node. (Note that Period 1 is the second purchase opportunity for the customer: The first purchase opportunity occurred during the acquisition period. The probability that a customer will reach the current state of one purchase in the last 0-6 months is 1.0, because by definition the customer has purchased once already.)

For example, looking at Table Retention-9, there is a .2 probability that a customer will buy in Period 1. (This corresponds to the buying probability listed in the first, upper-left cell of the RFM matrix in Table Retention-8.) Thus, there remains a .8 probability that the customer will not buy in Period 1. If the customer does not buy, then he advances to the current state of one purchase in the last 7-12 months, where there is a .9 (.9=1-.
a) probability that he will again not buy. If the customer again does not buy, he advances to the current state of one purchase in the last 13-18 months. Therefore, the probability that a given customer will reach this state, one purchase in the last 13-18 months, equals .8 times .9 = .72.
Step 7: Compute the profitability of a customer at each terminal state. To determine the profitability of each path, start by counting up the number of purchases (i.e., buy decisions) that the customer has made, not including the first purchase. Multiply this purchase number by the dollar margin per purchase, and then subtract the per-customer marketing costs for each period. This gives the per customer profit for that path.
Step 8: Compute the expected retention equity per customer. This is done by multiplying the probability that a customer will reach a given terminal state by the payout once the customer has reached it. For each terminal state, Table Retention-9 shows the probability of reaching it along with its profit per customer. Multiplying this profit per customer by the probability yields an expected profit for the terminal state. The sum of the expected profits for all terminal states equals retention equity per customer. That value for this example is $1,035.44.
 
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